A cellphone surveillance tool often acquired by law enforcement agencies under the guise of homeland security is being used in at least one community for broad criminal investigations, TheBlot Magazine has learned.

The acknowledgement comes as police departments at the state and local level are increasingly being told by federal officials to keep quiet about their acquisition and use of intrusive technology that critics charge with violating the Constitutional rights of citizens.

The surveillance device, known as a “Stingray,” is believed to be in use by dozens of local and state law enforcement agencies throughout the United States. The device, manufactured and sold by the Florida-based Harris Corporation, acts as a fake cellphone tower, forcing all mobile phones within a certain radius to connect to it instead of a legitimate tower.

Documents obtained by various news organizations — including a series of documents published by Sacramento TV station KXTV — show that police departments across the country are obtaining Stingrays through federal homeland security grants. In their applications, many agencies claim Stingrays will help them combat terrorism.

But TheBlot has learned one community that has access to such a device is not limited to terrorism investigations and may be using the spy tool in routine criminal investigations.

Four years ago, the community of Gwinnett County, Ga., approved more than $300,000 for the local police department to purchase both a Stingray device and a portable Stingray called a Kingfish from Harris. An invoice obtained by TheBlot shows that the department spent $199,700 of the earmarked money on the surveillance devices as well as accessories and training.

When asked if the devices are limited to serious criminal cases such as homicide or homeland security investigations, police spokesperson Jake Smith said the surveillance tools are used “in criminal investigations with no restrictions on the type of crime.”

The acknowledgement from one law enforcement agency that a surveillance tool reserved for homeland security investigations was being used in routine criminal matters has been long suspect and didn’t come as a surprise to one privacy advocate TheBlot spoke with.

“I think what happens is the police agencies use ‘homeland security’ to get grant funds from DHS and other agencies to purchase the device, explain to city councils why they need the device and how it can be paid for, and get around open bidding laws,” said Electronic Frontier Foundation staff attorney Hanni Fakhoury. “But once they get the device, they use them pretty much for whatever they want, including regular domestic crime investigation.”

Police have argued that confidentiality agreements between their departments and Harris preclude them from disclosing their use of the surveillance tools in criminal proceedings. At least one recent invoice examined by TheBlot shows that Harris currently warns law enforcement agencies that the disclosure of information about clandestine surveillance tools and associated documents — including the invoices themselves — is a violation of federal law.

But the 2010 Gwinnett County police invoice offers no such warning, suggesting that Harris only recently began enforcing its nondisclosure agreement with law enforcement agencies to include documents related to the purchase of its surveillance tools.

While the Gwinnett County Police Department was transparent about its purchase and use of a Stingray, others have not been so forthcoming: Earlier this month, the Sacramento County Sheriff’s Department said it would withhold documents related to its use of Stingrays following an open records request filed by TheBlot in June. The agency cited several laws, including one dealing with the manufacture and trade of military weapons, as its reason for denying the request. It had previously told a local television station it “did not own or use Stingrays” and had “no records responsive” to a similar request made in February.